Method of fluid delivery and catheters for use with same

ABSTRACT

A pain management system for the infusion of drug to a wound site includes a guide needle placed within an introducer tubing. The needle and tubing are pierced through the patient&#39;s skin, after which the guide needle is withdrawn. The infusion catheter is threaded through the introducer tubing and advanced to the wound site. The introducer tubing is withdrawn and preferably peeled off of the infusion catheter. In accordance with one embodiment, the catheter comprises an elongated tube with a plurality of exit holes along an infusion section of the catheter, and an elongated flexible porous member residing within the tube and forming an annular space between the tube and the member. In accordance with other embodiments, the catheter includes a plurality of exit holes, which combine to form a flow-restricting orifice of the catheter.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.09/815,888 filed Mar. 23, 2001, now U.S. Pat. No. 6,626,885 which is acontinuation-in-part of International application no. PCT/US00/19746filed Jul. 19, 2000 which is a continuation-in-part of U.S. applicationSer. No. 09/363,228 filed Jul. 19, 1999 now U.S. Pat. No. 6,350,253.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to liquid dispensing systems, and morespecifically to a catheter-based system for infusing a liquid into thebody of a patient, and most specifically to a pain management systemwhich administers a post-operative drug to a wound site of a patientthrough a catheter that delivers fluid medication uniformly and at aknown rate across an infusion section of the catheter.

2. Description of Related Art

Patient trauma, pain and discomfort resulting from surgery or otherprocedures is routinely managed through the administration of narcoticsor non-narcotic drugs. Narcotics are generally disfavored as a painmanagement system because they affect the entire physical and mentalwell-being of the patient rather than only the local physical area ofconcern. Narcotics also have a variety of undesirable side effects, suchas nausea, vomiting, bowel retention, respiratory depression, inhibitionof the cognitive process, alteration of appetite, and potentiallycausing addiction. If used, narcotics can be administered through avariety of known ways, such as intramuscular injection, epiduralinjection, intravenous injection or orally.

Post-operative pain management is commonly addressed by administeringnon-narcotic drugs to the patient. Typically, the drug is administereddirectly into the epidural space of the patient for a period of severaldays following surgery. However, administering narcotics or non-narcoticdrugs into the patient often necessitates monitoring by hospital staffand additional hospital stay due to the side effects of the drugs orbecause patients cannot be sent home with the required equipment toadminister the drugs.

One direct-site drug administration procedure involves using a syringeand needle several times per day to inject the drug at or near the sitewhere the surgeon made the incision through the patient's skin, withseveral needle pierces made during each dose application. Because manyneedle pierces are cumulatively made at or near the sensitive incisionsite, this administration procedure further aggravates patient trauma,pain and discomfort.

Another direct site drug administration procedure involves placing adrug directly into a wound site prior to a surgeon closing the wound.However, this procedure typically lasts only approximately four to sixhours and patients often need pain management at a wound site for far inexcess of this time period.

A need therefore exists for a pain management system which reducespatient trauma, pain and discomfort resulting from surgery or otherprocedures. A need also exists for a drug administration system whichdoes not require repeated needle piercings at or near the sensitiveincision site. Additionally, there exists a need for a portable drugadministration system that a patient can take home to reduce thepatient's hospital stay. Finally, there is a need for a dispensingsystem that dispenses a liquid from a first location to a secondlocation at a predictable and known rate.

In addition to the prior art limitations and needs described above,there are also certain limitations with infusion catheters that areoften used in pain management systems. Infusion catheters, which arewell known in the art, generally include a flexible hollow tube insertedinto some region of the anatomy. The tube typically contains one or moreaxial lumens within which the fluid may flow. The proximal end of thecatheter tube is connected to a fluid source from which fluid isintroduced into the catheter tube. The fluid flows within one of thelumens under pressure supplied at the proximal end of the tube. For eachlumen, there are commonly provided one or more exit holes along aninfusion section near the distal end of the tube, for fluid to exit thetube. Such exit holes may be created by piercing the side wall of thehollow tube.

In certain medical conditions, it is advantageous to deliver fluidmedication to a plurality of sites within a wound area. For instance,some wounds which require pain medication may be in communication withmany nerve endings, rather than a single nerve trunk. One example ofsuch a wound is a surgical incision. As stated above, it is known toprovide a plurality of exit holes through which the fluid medicationexits the catheter tube. The exit holes may be provided at various axialand circumferential positions along the catheter tube in order tocontrol the position of the medication delivery sites. An example of acatheter having this configuration is disclosed in U.S. Pat. No.5,800,407 to Eldor. Also, in some cases it is desirable to deliver suchmedication under low pressure, so that the fluid is delivered at arelatively low rate. For example, some pain medications must bedelivered slowly to avoid toxicity and other side effects. Furthermore,in many cases it is desirable to dispense fluid medication at asubstantially uniform rate throughout the infusion section of thecatheter, so that the medication is evenly distributed throughout thewound area.

Unfortunately, a limitation of prior art catheters with multiple exitholes, such as the catheter taught by Eldor, is that during low pressuredelivery of fluid medication the fluid tends to exit only through theexit hole(s) nearest to the proximal end of the infusion section of thecatheter tube. This is because fluids flowing through a tube morereadily exit through the exit holes offering the least flow resistance.The longer the flow path followed by the fluid in the lumen, the higherthe flow resistance and pressure drop experienced by the fluid. The mostproximal holes offer the least flow resistance and pressure drop.Therefore, the fluid tends to exit the catheter tube primarily throughthese exit holes. As a result, the fluid medication is delivered only toa small region within the wound area. The tendency of the fluid toundesirably flow only through the most proximal exit holes depends uponthe hole size, the total number of exit holes, and the flow rate. As,the hole size or number of holes increases, the fluid becomes morelikely to exit only through the most proximal holes. Conversely, as theflow rate increases, the fluid becomes less likely to do so.

The tendency of the fluid to undesirably exit only through the mostproximal holes of the catheter can in some cases be overcome byincreasing the flow rate or pressure of the fluid, which causes thefluid to flow through more of the exit holes of the catheter. Indeed, ifthe flow rate or pressure is sufficiently high, the fluid will flowthrough all of the exit holes. However, sometimes it is medicallydesirable to deliver medication at a relatively slow rate, i.e., at alow pressure. Also, even in those cases in which high-pressure fluiddelivery is acceptable or desirable, prior art catheters do not providefor uniform fluid delivery along the infusion section of the catheter.Rather, the flow rate through the exit holes nearer to the proximal endof the infusion section tends to be greater than that through the exitholes nearer to the distal end. This is because the fluid passingthrough the more proximal holes experiences a lower flow resistance andpressure drop. In contrast, the fluid flowing through the more distalholes experiences greater flow resistance and pressure drop, andconsequently exits at a lower flow rate. The further distal the hole,the lower the exit flow rate of the fluid. As a result, there is anuneven distribution of medication throughout the wound area.

In another known type of infusion catheter, several lumens are providedwithin a catheter tube. For each lumen, one exit hole is provided bypiercing a hole within the wall of the tube. The exit holes are providedat different axial positions along the infusion section of the cathetertube. In this manner, fluid medication may be delivered to severalpositions within the wound area. While this configuration offersimproved fluid distribution, it has some disadvantages. One disadvantageis that the fluid flow rates through the exit holes are not equal, sincethe more distal exit holes offer a greater flow resistance for the samereasons discussed above. Another disadvantage is that the number oflumens, and consequently the number of fluid exit holes, is limited bythe small diameter of the catheter tube. As a result, fluid may bedelivered only to a very limited number of positions within the woundarea. Yet another disadvantage is that the proximal ends of the lumensmust be attached to a complicated manifold which increases the cost ofmanufacturing the catheter.

An example of a catheter providing a more uniform dispensation of fluidmedication throughout an infusion section of the catheter is illustratedby U.S. Pat. No. 5,425,723 to Wang. Wang discloses an infusion catheterincluding an outer tube, an inner tube concentrically enclosed withinthe outer tube, and a central lumen within the inner tube. The innertube has a smaller diameter than the outer tube, so that an annularpassageway is formed therebetween. The outer tube has a plurality ofevenly spaced exit holes defining the infusion section of the catheter.In use, fluid flowing within the central lumen passes throughstrategically positioned side holes within the side walls of the innertube. In particular, the spacing between adjacent side holes decreasesalong a length of the inner tube to induce more fluid to pass throughthe more distal side holes. The fluid then flows longitudinally throughthe annular passageway before exiting through the exit holes in theouter tube wall. In the annular passageway, the fluid can flow in adistal or proximal direction, depending on the location of the nearestexit hole in the outer tube. This configuration is provided to induce amore uniform exit flow rate of fluid from the catheter.

Unfortunately, the Wang catheter is only effective for relatively highpressure fluid delivery. When used for relatively low pressure fluiddelivery, the catheter disclosed by Wang does not provide uniformdispensation of fluid. Instead, the fluid tends to exit through the sideholes of the inner and outer tubes that are nearest to the proximal endof the infusion section of the catheter, since these holes offer theleast flow resistance. Even for high pressure fluid delivery, there areseveral limitations of this design. One limitation is that theconcentric tube design is relatively complex and difficult tomanufacture. Both tubes must be flexible enough to permitmaneuverability through an anatomical system, yet the annular passagewaymust remain open so that fluid may flow uniformly therein. Anotherlimitation is that the annular passageway may be disturbed if there is abend in the infusion section of the tube. A bend in the catheter maydeform the annular passageway or even cause the inner and outer tubes tocome into contact. This can cause an uneven fluid pressure within alongitudinal cross-section of the annular passageway, resulting innon-uniform fluid delivery.

Thus, there exists a need for an improved pain management system, usingan improved infusion catheter for delivering fluid medication uniformlyalong its infusion section. It should come in a relatively simple, easyto manufacture design which is effective for both high flow rate and lowflow rate fluid delivery. Furthermore, it is recognized that aparticular class of catheters, such as the Wang catheter, may provideuniform fluid delivery only at high fluid pressure or flow rates.However, there is a need for an infusion catheter belonging to thisclass that has a relatively simple, easy to manufacture design and canmaintain uniform fluid delivery while bent or otherwise physicallydeformed.

SUMMARY OF THE INVENTION

One aspect of the present invention provides a portable pain managementsystem for the post-operative infusion of a non-narcotic local drug tothe wound site of a patient. The system achieves this function withoutpiercing the sensitive incision site and instead pierces the patient'sskin at a pierce site at a distance from the incision site.

Briefly stated, the system provides a pump connected to medical tubing.The medical tubing, in turn, is connected to a unique catheter. Thecatheter is inserted into the body of a patient at a pierce site andadvanced within the patient's body to the wound site. A clamp, filter,and/or flow controller may be positioned along a portion of the medicaltubing to assist in providing the drug at a predicable and known rate tothe wound site.

In operation, when the infusion pump is loaded with the drug, the pumpimparts a pressure on the drug. This constant pressure causes the drugto flow from the pump, through the medical tubing, through the catheter,into the patient's body, and to the wound site.

The procedure of inserting the unique catheter into the patient's bodymay be performed prior to loading the pump with the drug. Alternatively,the catheter may be inserted after the pump is loaded with the drug. Inaccordance with one preferred procedure, a guide needle is placed withinan introducer tubing. After that, the needle/tubing assembly is piercedthrough the patient's skin at a site spaced from the incision site. Theguide needle is then withdrawn and discarded, leaving the introducertubing in place partially under the patient's skin, so the uniquecatheter can be threaded through the introducer tubing and advanced tothe wound site. The introducer tubing is then withdrawn and discardedwhile the unique catheter remains in place to administer the drug to thewound site. Preferably, the introducer tubing may be peeled off of theunique catheter into two pieces so that the unique catheter may beintegrally secured to a hub prior to use.

Insertion of the guide needle at a remote pierce site rather than at theincision site is advantageous for many reasons. The spaced insertionlocation keeps the incision site cleaner and decreases the potential forinfection at the incision site. Further, the remote insertion locationassists in the proper formation of scar tissue at the incision site,which would otherwise be hindered by insertion of a needle through theincision site. This insertion technique also provides a more secure basethrough which the catheter enters into the patient's body and minimizescatheter removal problems. One skilled in the art will understand thatother advantages to using this remote insertion location exist.

Accordingly, it is another principle object and advantage of the presentinvention to overcome some or all of these limitations by providing animproved catheter for delivering fluid medication to the wound area ofan anatomical region.

In accordance with one embodiment of the present invention, the catheterprovides for the uniform delivery of fluid across an anatomical region,and comprises an elongated tubular member made of a porous membrane. Themembrane is sized to be inserted through a subcutaneous layersurrounding the anatomical region, such as a person's skin. The membraneis configured so that a fluid introduced under pressure into an open endof the tubular member will flow through side walls of the tubular memberat a substantially uniform rate along a length of the tubular member.The present invention also provides a method of uniformly deliveringfluid throughout an anatomical region, comprising the steps of insertingthe elongated tubular member into the anatomical region and introducinga fluid under pressure into an open end of the tubular member.

Another embodiment of the present invention provides a catheter andmethod for the uniform delivery of fluid throughout an anatomicalregion. The catheter comprises an elongated support and a porousmembrane wrapped around the support. The support is configured so thatone or more lumens are formed between the support and the membrane.Alternatively, the support may be a tubular member having a plurality ofholes therein. The method comprises the steps of inserting theabove-described catheter into the anatomical region and introducing afluid under pressure into the proximal end of at least one of thelumens. Advantageously, the fluid passes through the membrane at asubstantially uniform rate into the anatomical region. The presentinvention further provides a method of manufacturing this cathetercomprising the steps of forming an elongated support and wrapping aporous membrane around the support so that one or more lumens are formedbetween the support and the membrane.

Another embodiment of the present invention provides a catheter andmethod for the uniform delivery of fluid throughout an anatomicalregion. The catheter comprises an elongated tube including a pluralityof exit holes along a length thereof and a tubular porous membraneconcentrically enclosed within the tube. The tube and membrane define alumen. The method comprises the steps of inserting the above-mentionedcatheter into the anatomical region and introducing a fluid underpressure into the proximal end of the lumen so that the fluidadvantageously passes through the membrane and the exit holes at asubstantially uniform rate into the anatomical region. The presentinvention further provides a method of manufacturing this catheter,comprising the steps of forming an elongated tube, providing a pluralityof exit holes along a length of the tube, forming a tubular porousmembrane, and concentrically enclosing the tubular porous membranewithin the tube so that the tube and membrane define a lumen.

Yet another embodiment of the present invention provides a device andmethod for the uniform delivery of fluid throughout an anatomicalregion. The device is advantageously simple and easy to manufacture,comprising an elongated catheter having a plurality of exit holes alonga length thereof. The exit holes may serve as the flow-restrictingorifice. Alternatively, a flow-restricting orifice may be providedelsewhere within the catheter or proximal to the catheter. The exitholes may gradually increase in size along the length of the catheter,so that the largest exit hole is further distal than the smallest exithole. Alternatively, the holes can be laser drilled and be ofapproximately the same size. Advantageously, a fluid flowing underpressure within the catheter will flow through substantially all of theexit holes at a substantially equal rate. The method comprises the stepsof inserting the catheter into the anatomical region and introducing afluid under pressure into the proximal end of the catheter. The fluidflows through the exit holes and enters the anatomical region,advantageously flowing through substantially all of the exit holes at asubstantially equal rate. The present invention further provides amethod of manufacturing this device, comprising the steps of forming anelongated catheter and providing a plurality of exit holes along alength of the catheter in a manner so that the exit holes graduallyincrease in size along the length of the catheter from the proximal endto the distal end thereof.

Yet another embodiment of the present invention provides a catheter andmethod for delivering fluid medication to an anatomical region. Thecatheter comprises a tube, a “weeping” tubular coil spring attached to adistal end of the tube, and a stop closing a distal end of the spring.The tube and spring each define a portion of a central lumen. The springhas adjacent coils in contact with one another so that fluid within thespring and below a threshold dispensation pressure is prevented fromexiting the lumen by flowing radially between the coils. The spring hasthe property of stretching when the fluid pressure is greater than orequal to the threshold dispensation pressure permitting the fluid to bedispensed from the lumen by flowing radially between the coils, i.e.“weeping” through the spring. Alternatively, the fluid may weep throughimperfections in the spring coil. Advantageously, the fluid is dispensedsubstantially uniformly throughout the length and circumference of aportion of the spring. In use, fluid is introduced into an open proximalend of the tube, allowed to flow into the spring, and brought to apressure greater than or equal to the threshold dispensation pressure sothat the fluid weeps through the spring.

Yet another embodiment of the present invention provides a catheter andmethod for delivering fluid medication to an anatomical region. Thecatheter comprises a distally closed tube and a “weeping” tubular coilspring, as described above, concentrically enclosed within the tube. Aplurality of exit holes are provided in side walls along a length of thetube, defining an infusion section of the tube. The spring is enclosedwithin the infusion section so that a lumen, is defined within the tubeand spring. In use, fluid is introduced into a proximal end of the tube,allowed to flow into the spring, and brought to a pressure greater thanor equal to the threshold dispensation pressure of the spring so thatthe fluid is dispensed from the lumen by weeping through the spring andthen flowing through the exit holes of the tube.

Yet another embodiment of the present invention provides a cathetercomprising an elongated tube and a solid flexible member positionedwithin the tube. The tube has a closed distal end and a plurality ofexit holes in side walls of the tube. The exit holes are provided alonga length of the tube defining an infusion section of the catheter. Thetube is sized to be inserted into an anatomical region. The member ispositioned within the tube and is sized so that an annular space isformed between the tube and the member. The member is formed of a porousmaterial. Advantageously, the catheter is configured so that a fluidintroduced into a proximal end of the tube will flow through the exitholes at a substantially uniform rate throughout the infusion section.

In yet another embodiment, the present invention provides a cathetercomprising an elongated tube having a plurality of exit slots in sidewalls of the tube. The slots are provided along a length of the tubedefining an infusion section of the catheter. The exit slots areoriented generally parallel to the longitudinal axis of the tube.Advantageously, the tube is configured so that a fluid flowing thereinwill flow through substantially all of the exit slots at a substantiallyequal rate. In one optional aspect, the slots increase or decrease inlength from the proximal to the distal ends of the infusion section. Inyet another embodiment of the present invention, exit holes along thecatheter may be unevenly spaced to achieve more even flow of fluidthroughout the infusion section of the catheter. For example, theproximal end of the infusion section may have a first distance betweenadjacent holes and the distal end of the infusion section may have asecond, shorter distance between adjacent holes. Alternatively, thedistance between adjacent holes can decrease in the distal direction.

For purposes of summarizing the invention and the advantages achievedover the prior art, certain objects and advantages of the invention havebeen described hereinabove. Of course, it is to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught herein without necessarilyachieving other objects or advantages as may be taught or suggestedherein.

All of these embodiments are intended to be within the scope of theinvention herein disclosed. These and other embodiments of the presentinvention will become readily apparent to those skilled in the art fromthe following detailed description of the preferred embodiments havingreference to the attached figures, the invention not being limited toany particular preferred embodiment(s) disclosed.

Further aspects, features and advantages of the present invention willbecome. apparent from the following drawings and detailed descriptionintended to illustrate but not to limit the concepts of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the liquid dispensing system of thepresent invention, illustrating a general orientation of the system whenused with a post-surgical medical patient having a wound;

FIG. 2 is a top plan view, showing additional system elements;

FIG. 3A is a side elevational view of a guide needle surrounded byintroducer tubing;

FIG. 3B is a side elevational view of a guide needle surrounded by aunique, peel-away introducer tubing;

FIG. 4 is a schematic view of a pierce site of the patient of FIG. 1,showing the needle/tubing assembly of FIG. 3 pierced through thepatient's skin at the pierce site, the pierce site being spaced from anincision site;

FIG. 5 is a schematic, cross sectional view, showing the needle/tubingassembly of FIG. 3 pierced through the patient's skin at the pierce siteand extending to the wound site;

FIG. 6 is a view similar to FIG. 5, showing the guide needle withdrawnfrom the introducer tubing and a portion of the introducer tubingremaining in place partially under the patient's skin;

FIG. 7 is a view similar to FIG. 6, showing a catheter threaded throughthe introducer tubing and advanced along the wound site;

FIG. 8 is a view similar to FIG. 7, showing the introducer tubingwithdrawn from the patient's body and the catheter in place at the woundsite;

FIG. 9 is a schematic, cross sectional view, showing the downstream endof the catheter with a plurality of holes formed thereon; and

FIG. 10 is a view similar to FIG. 9, showing an alternative downstreamend of the catheter.

FIG. 11 is a schematic side view of a catheter having features andadvantages in accordance with the present invention;

FIG. 12 is a sectional view of the catheter of FIG. 11, taken along line12-12 of FIG. 11;

FIG. 13 is a sectional view of the catheter of FIG. 11, taken along line13-13 of FIG. 11;

FIG. 14 is a perspective view of the end portion and support beam of thecatheter of FIG. 11, illustrating a cross-section taken along line 14-14of FIG. 11;

FIG. 15 is a side view of a catheter having features and advantages inaccordance with another embodiment of the present invention;

FIG. 16 is a cross-sectional view of the infusion section of thecatheter of FIG. 15 taken along line 16-16 of FIG. 15;

FIG. 17 is a cross-sectional view of a catheter having features andadvantages in accordance with another embodiment of the presentinvention;

FIG. 18A is a side view of a catheter having features and advantages inaccordance with another embodiment of the present invention;

FIG. 18B is a side view of a catheter having features and advantages inaccordance with another embodiment of the present invention;

FIG. 18C is a side view of a catheter having features and advantages inaccordance with another embodiment of the present invention;

FIG. 19 is a side view of a catheter having features and advantages inaccordance with another embodiment of the present invention;

FIG. 20A is a cross-sectional view of the catheter of FIG. 19,illustrating an unstretched state of the spring;

FIG. 20B is a cross-sectional view of the catheter of FIG. 19,illustrating a stretched state of the spring;

FIG. 21 is a cross-sectional view of a catheter having features andadvantages in accordance with another embodiment of the presentinvention;

FIG. 22 is a side view of a catheter having features and advantages inaccordance with the embodiment of FIG. 21;

FIG. 23 is a longitudinal cross-sectional view of a catheter havingfeatures and advantages in accordance with another embodiment of thepresent invention;

FIGS. 24-26 are longitudinal cross-sectional views of catheters similarto that of FIG. 23, illustrating alternative attachments between theinternal porous member and the tube;

FIG. 27 is a transverse cross-sectional view of a catheter according toFIGS. 23-26, wherein the internal porous member is concentric with theouter tube;

FIG. 28 is a transverse cross-sectional view of a catheter according toFIGS. 23-26, wherein the internal porous member is not concentric withthe outer tube;

FIG. 29 is a schematic illustration of a catheter of the presentinvention used in conjunction with an air eliminating filter;

FIG. 30 is a side view of a catheter having features and advantages inaccordance with another embodiment of the present invention;

FIG. 31 is a side view of a catheter having features and advantages inaccordance with another embodiment of the present invention; and

FIG. 32 is a schematic illustration of the use of a catheter of thepresent invention for treating a blood clot.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiment of the liquid dispensing system is illustratedin the context of an exemplary pain management system which administersa drug into the body of a patient that has undergone arthroscopicshoulder surgery. However, the pain management system can be used withany type of surgical procedure, and on any portion of the patient'sbody, such as knees, elbows and the like. The principles of the presentinvention, moreover, are not limited to administering a drug or infusinga liquid into the body of a patient. Instead, it will be understood byone of skill in the art, in light of the present disclosure, that thedispensing system disclosed herein can be used to introduce or removeother materials from a wound site or other area within a patient.

To assist in the description of the system and method of use disclosedherein, the following terms are used. The term “distal” refers to a sitethat is away from a specified site. The term “proximal” refers to a sitethat is close to a specified site. Expressed alternatively, a sitetermed “proximal” is measurably closer to a specified reference pointthan a site termed “distal.” The term “downstream” refers to directionalmovement of the liquid drug from the infusion pump to the wound site. Anobject or site referred to as “downstream” of another object or sitemeans that the “downstream” object or site is proximal the wound siterelative to the other object or site. Similarly, an object or sitereferred to as “upstream” to another object or site means that the“upstream” object or site is proximal the infusion pump site relative tothe other object or site. Expressed alternatively, the “downstream”object is proximal the wound site and the “upstream” object is distalthe wound site.

The “wound site” is the area within the body of the patient where thesurgical procedure was performed. The “incision site” is the area wherethe surgeon entered through the patient's skin to arrive at the woundsite. The incision site need not be made by the surgeon, for example, apatient may have an open wound (e.g. knife incision) through which thesurgeon arrives at the wound site. The “pierce site” is the site wherethe patient's skin is pierced to allow the catheter to extendtherethrough and arrive at the wound site to administer the drug.

System Components

FIGS. 1 and 2 illustrate a liquid dispensing system 10 employing a pump20 connected to an inlet port 30 on one end and to medical tubing 70 onthe other end. The medical tubing 70, in turn, is connected to acatheter 76. The catheter 76 is inserted into the body of a patient at apierce site P, adjacent an incision site I, and advanced within thepatient's body to an interior wound site W (not shown in FIG. 1),thereby allowing application of the drug to the wound site W. A clamp36, filter 58, and/or flow controller 62 may be positioned along aportion of the medical tubing 70 to assist in providing the drug to thewound site W at a predicable and known rate.

Referring to FIG. 2, the infusion pump 20 preferably accommodates up toabout 500 ml of drug and more preferably up to about 100 ml. The pump 20can impart pressure on the drug, causing the drug to flow out of thepump at a predictable rate. The illustrated pump has an inner core 22,elastomeric bladder 24 and a housing 26, which define a reservoir 28.The illustrated pump 20 is described in U.S. Pat. No. 5,284,481 assignedto I-Flow Corporation, which is hereby incorporated by reference.However, a variety of other conventional infusion pumps may be used, solong as they can impart a pressure on the drug. For example, the pumpsdescribed in U.S. Pat. Nos. 5,080,652 and 5,105,983 both assigned toI-Flow Corporation, which are hereby incorporated by reference may beused, as well as other suitable electronic or mechanical pumps offeredby many other manufacturers.

An inlet valve or injection port 30 at an upstream end 32 of theinfusion pump 20 delivers the drug into the inner core 22 of the pump20. The injection port 30 is sized and configured to removablyinterconnect with a conventional syringe (not shown) to load the druginto the infusion pump 20. The interconnection between the injectionport 30 and the syringe may be achieved by mating threadings, tapers,ends or other suitable configurations, as will be understood by one ofskill in the art. When not connected to the syringe, the injection port30 is sealed and may be protected by an injection cap 34 connected tothe injection port 30.

A clamp 36 arranged downstream of the infusion pump 20 can compress themedical tubing 70, so that fluid flow is occluded. The illustratedembodiment shows the clamp 36 having a pair of opposing projections 42and 40 respectively extending from a first wall 46 and a second spacedwall 44. At least one of the walls is sufficiently flexible so that thewalls can be moved closer together. When the walls are advancedsufficiently close, the projections 40 and 42 are advanced to a positionin which the space between them is reduced sufficient to pinch themedical tubing 70 and occlude fluid flow. A recess 47 is preferablyformed on the first wall 46 and an extension 48 is preferably formed onthe second wall 44. When the walls 46 and 44 are advanced sufficientlyclose to occlude fluid flow through the medical tubing 70, the recess 47and extension 48 removably interlock to maintain the occlusion. Thearrangement of the recess 47 and extension 48 may be reversed, and othersuitable interlocking means may also be used. First and second openings51 and 52 can be arranged on opposing ends 54 and 56 of the clamp 36 soit can slide along a length of the medical tubing 70 and occlude variousportions of the tubing. As will be understood by one of skill in theart, a variety of other conventional clamps can be used to achieve theocclusion function. For example, roller clamps, stopcocks and otherclamps known in the industry may be used to occlude flow of fluid fromthe pump 20 through the tubing 70.

Still referring to FIG. 2, a filter 58 downstream of the clamp 36separates the drug from contaminates and other undesired particles thatmay be found within the drug. The filter 58 also eliminates air from thefluid path. The illustrated embodiment shows the filter 58 having aporous membrane 60 which captures the contaminates and other undesiredparticles, while allowing the drug to pass through the porous membrane60. The capture may be performed by a variety of methods to includephysical capture, where the size of the porous member 60 selectivelyperforms the capture; chemical capture, where the composition of theporous member 60 selectively performs the capture; or other suitablecapture methods which separate the drug from contaminates and otherundesired particles.

A flow controller 62 arranged downstream of the filter 58 assists inmaintaining a predicable and known flow of the drug to the wound site W.At least a portion of the flow controller 62 has a micro-bore cannula 64with a predetermined constant lumen radius and a predetermined constantlumen length. By this configuration, a dam effect is provided where theupstream end 66 of the cannula 64 may be analogized to a reservoir, andthe downstream end 68 of the cannula 64 enjoys a predicable, known flowrate. However, any other suitable device may be used to perform the flowcontrol function including, but not limited to, the catheter itself.

Although FIG. 2 shows the clamp 36, filter 58 and flow controller 62arranged on the medical tubing 70, these elements are merelyadvantageous to use and are not required, as shown in FIG. 1, whichillustrates only the optional clamp 36 and flow controller 62 in use.FIG. 2 also shows the clamp 36 upstream of the filter 58, which isupstream of the flow controller 62. However, this particular arrangementis merely exemplary. FIG. 2 further shows only a single clamp 36, filter58 and flow controller 62 used, however, a plurality of any of theseelements may be used. Moreover, the clamp 36, filter 58 and/or flowcontroller 62 may be integral with the pump 20. Thus, any combination ofthese elements may be present in the fluid tubing 70.

Still referring to FIG. 2, medical tubing 70 extends from at least thedownstream end of the infusion pump 36 to at least an upstream end of acatheter connector 72 (detailed below). The illustrated embodiment showsthe medical tubing 70 as a one-piece assemblage formed with the infusionpump 20, clamp 36, filter 58 and flow controller 62. However, theassembly need not be unitary. Rather, one or more connectors 74, such asa conventional luer-lock connectors, may be used to modularly connectone or more segments of medical tubing 70 and/or elements of the systemto each other. Also, the medical tubing 70 need not have a uniformdiameter.

The catheter connector 72 at the downstream end of the medical tubing 70is illustrated as a conventional Toughy Borst connector. The connector72 connects the distal end of the tubing 70 (via a luer lock 74 attachedto the distal end of the tubing 74) to the proximal end of a catheter76.

In another improved method, the catheter 76 may be secured to a hub (notshown) prior to connection of the hub to the distal end of the tubing70. This arrangement is advantageous so that a physician or healthcareworker does not need to accomplish the added step of securing thecatheter 76 to the connector 72.

In one example, a 20 gage catheter 76 having a length of about 100 cmwas found to be satisfactory. Of course, the catheter may be of anylength desired by the healthcare worker. The downstream end of thecatheter desirably has a plurality of holes 77 to assist in dispensingthe drug throughput the wound site W. See FIGS. 9 and 10. The holes 77are arranged along a length of the catheter 76 that can range from about1-200 cm, depending on the length of the wound site W. The diameter ofthe holes 77 may be of varied size relative to the downstream end of thecatheter 76 to assist in equal distribution of the drug along the woundsite W. Additional embodiments of the catheter are discussed in detailbelow. As those of skill in the art can appreciate, the methodsdescribed herein may be used with any of the catheter embodimentsdiscussed herein. For example, the method may be used with any catheterdescribed and illustrated in FIGS. 9-31 or with any other cathetermanufactured by any entity.

Alternatively, instead of connecting the pump 20 to the tubing 70 andthe tubing 70 to the catheter 76. The pump 20, tubing 70 and catheter 76can be bonded or otherwise permanently secured to comprise a unitaryone-piece member. Unitary construction presents several advantages. Forexample, unitary construction obviates improper connection of theluer-lock connector 74 and Toughy Borst connector 72 or catheter hub.That is, if the connectors 72, 74 are connected loosely, fluid leakageor accidental disconnection of components may occur. Similarly, if theconnectors 72, 74 are connected too tight, the connector threads maystrip. For another example, unitary construction obviates lost ormisplaced components. A unitary construction may be preferred if theportable liquid dispensing system 10 is used by a patient at homewithout the benefit of continuous medical supervision.

Illustrative Catheter Insertion Methods

Referring to FIGS. 3-8, a preferred procedure to insert the catheter 76into the patient's body at the pierce site P, spaced from the incisionsite I, and advance the catheter 76 to the wound site W is illustrated.

Referring to FIGS. 3A and 4, a guide needle 78 comprises a conventionalmedical needle or rod having a pointed end 80 sufficiently sharp topierce and penetrate the patient's skin. The guide needle 78 may behollow or solid without any lumen therethrough. An introducer tubing 82has a diameter sufficient to allow the guide needle 78 to be placedtherein. The introducer tubing or conduit 82 is sufficiently rigid sothat it can extend through the pierce site P and into the patient's bodywithout significantly bending away from the guide needle 78 uponpenetration through the skin.

At least a portion of the guide needle 78 is placed within at least aportion of the introducer tubing 82 to form a needle/tubing assembly 84.When the needle/tubing assembly 84 is formed, the end 80 of the guideneedle 78 preferably extends beyond the end 86 of the introducer tubing82 so that the end 80 of the guide needle 78 initially pierces thepatient's skin at the pierce site P and then the end 86 of theintroducer tubing 82 extends through the pierce site P.

The needle/tubing assembly 84 cooperates so that when the guide needle78 and introducer tubing 82 pierce the skin and are advanced into thepatient to form a passage, neither the guide needle 78 nor introducertubing 82 appreciably move relative to each other, yet, when the guideneedle 78 is withdrawn, the guide needle 78 separates from theintroducer tubing 82 and at least a portion of the introducer tubing 82remains within the patient. This cooperation can be achieved in avariety of ways. One way is to provide a taper 88 on the introducertubing 82 so that the downstream end 90 has a smaller diameter than theupstream end 92. Thus, when the needle/tubing assembly 84 is advanced,the downstream outer diameter 94 of the guide needle 78 contacts thedownstream inner diameter 90 of the introducer tubing 82, yet when theneedle/tubing assembly 84 is withdrawn, the upstream outer diameter 96of the guide needle 78 does not contact the upstream inner diameter 92of the introducer tubing 82. Another way this cooperation can beachieved is to arrange an extension or stop 98 on the downstream end ofthe introducer tubing 82. The stop 98 prevents a protuberance 100 formedon the guide needle 78 and upstream of the stop 98 from advancingrelative to the introducer tubing 82 (the protuberance 100 has a largerdiameter than the stop 98), yet does not prevent the guide needle 78from being withdrawn from the introducer tubing 82.

Referring to FIGS. 4 and 5, once the guide needle 78 is placed withinthe introducer tubing 82, the needle/tubing assembly 84 is then piercedthrough the patient's skin at the pierce site P. The end 80 of the guideneedle 78 provides a clean skin pierce. The guide needle 78 preferablypierces the skin at an angle to assist in providing a clean pierce ofthe resilient skin. Use of the introducer tubing 82, rather than onlythe guide needle 78 is preferred, because the introducer tubing 82assists in threading the catheter 76 into the patient's body.

The pierce site P is sufficiently close to the wound site W so that whenthe introducer tubing 82 is advanced from the pierce site P to the woundsite W, it is not snagged, blocked or otherwise inhibited from reachingthe wound site W. The pierce site P is, however, sufficiently far fromboth the wound site W and the incision site I to diminish the likelihoodof infection at the wound site. The distance between the pierce site Pand the incision site I will depend on a variety of factors, such as thetype of drug used, the size of the needle/tubing assembly 84, and thesize and type of wound. In the illustrated procedure, the distancebetween the pierce site P and the incision site I can range from about1-10 cm, and more preferably from about 3-5 cm.

After the needle/tubing assembly 84 pierces the skin, it is advancedslightly into the patient's body, as explained below. The distance whichthe needle/tubing assembly 84 is advanced will depend on a variety offactors, as explained above.

Referring to FIG. 6, after the needle/tubing assembly 84 is in place,the guide needle 78 is withdrawn and safely discarded while theintroducer tubing 82 remains in place partially under the patient'sskin. The introducer tubing 82 forms a passage through which a catheter76 may be safely introduced into a wound site.

Referring to FIG. 7, after the guide needle 78 is withdrawn from theintroducer tubing 82, the catheter 76 is inserted into the introducertubing 82. The catheter 76 is then advanced from the pierce site P tothe wound site W. This advancement can be performed in a variety ofways. The illustrated embodiment shows the introducer tubing 82extending through the skin and into an end of the wound site Wsubcutaneously, with the catheter 76 subsequently advancing the lengthof the wound site W.

In accordance with another technique to advance the catheter 76 from thepierce site P to the wound site W, the catheter 76 is advanced through ahollow or open area (e.g. joint space) in the patient's body which is incontact with the wound site W. The hollow may or may not be filled witha liquid. This technique is similar to the illustrated technique, wherethe catheter extends through the introducer tubing and then advancesthrough the hollow to the wound site W.

Referring to FIG. 8, after the catheter insertion procedure isperformed, the introducer tubing 82 is withdrawn by backthreading itover the catheter 76 and removed from the upstream end of the catheter76. The upstream end of the catheter 76 is then connected to theconnector 72 which is then connected to medical tubing 70.

Alternatively, if a unitary liquid dispensing system 10 is used, asplit-introducer tubing 110 (FIG. 3B) is used to replace the introducertubing 82. That is, the above-described introducer tubing 82 cannot beused with a unitary system because the introducer tubing 82 cannot bebackthreaded off of the catheter 76 when the catheter 76 is permanentlyattached to a hub which will typically have a larger diameter than thetubing 82 so that the hub may be connected to the tubing 70.

FIG. 3B illustrates a split-introducer or conduit 110 thatadvantageously overcomes the backthreading requirement. Thesplit-introducer 110 is configured similar to the above-describedintroducer tubing 82, however, the split introducer 110 furthercomprises one or more hand-grip portions. The illustrated embodimentshows a pair of opposing hand-grip portions 112, 114 bonded to opposingsides of the split-introducer 110. The hand-grip portions 112, 114 aresized and configured so that a person can grasp them to pull thesplit-introducer 110 apart into opposing portions 116, 118. Thus, inpractice, once the catheter 76 has been threaded through the introducertubing or conduit 110 to the desired location, the introducer tubing 110is withdrawn from the patient while holding the catheter 76 in place.Once the introducer tubing 110 is removed from the body of a patient,the introducer 110 is split by a user into two portions or peeled awayfrom the catheter 76 and discarded.

The provision of a split introducer is advantageous so that thehealthcare worker does not need to thread the proximal end of thecatheter 76 into a connector 72. Often, healthcare workers are concernedthat tightening the connector 72 too tightly around the catheter 76 willocclude the catheter 76 and not permit fluid to flow therethrough. Thus,often healthcare workers do not tighten the connection sufficientlybetween the connector 72 and catheter 76 allowing fluid to leak from thesystem. As a result, it is preferable to have a catheter connected to ahub or connector 72 prior to insertion of the catheter through theintroducer tubing 110. The introducer tubing 110 eliminates the step ofsecuring the catheter 76 to the hub or connector 72, thereby eliminatingthe risk of catheter malfunction or introduction of contaminants whichcould enter the patient and cause harm.

The present invention contemplates that any conduit known to those ofskill in the art may be used in place of the introducer tubing 82 or thesplit introducer 110. Any such conduit is deemed to be within the scopeof the present invention.

A defined pattern of reduced strength 120 is preferably used to directthe separation of the split-introducer portions 116, 118 when thesplit-introducer 110 is pulled apart. The defined pattern of reducedstrength 120 can be embodied in a variety of configurations, such as oneor more score lines, or, as shown in the illustrated embodiment, as aportion of the split-introducer 110 having a thickness less than thethickness of another portion of the split-introducer 110.

One prior art method of introducing a catheter 76 to a wound site Wincludes using an introducer needle with a sharp point which is insertedthrough a pierce site P into a wound site W. The catheter 76 is thenthreaded through the introducer needle to the wound site W. Thereafter,the introducer needle is withdrawn from the patient while holding thecatheter in place. This prior art system has many disadvantages. Forexample, the healthcare worker must thread the needle off of thecatheter 76. This increases the chance of needle sticks and transfer ofdiseases such as AIDS and hepatitis from the patient to a healthcareworker. In addition, because an introducer needle has a sharp point topierce the skin of a patient, the introducer needle may undesirably ripthe catheter 76 which is typically manufactured from a lightweight,flexible material. Thus, by using an introducer tubing 84, 110, severaladvantages are obtained. First, the guide needle 78 can be safelyremoved from the introducer tubing and safely discarded without the riskof the introducer needle 78 coming in contact with a healthcare worker.In fact, many manufacturers, including B. Braun, sell introducerneedle/introducer catheter assemblies in which the needle is withdrawnfrom the interior of the introducer catheter without the risk of ahealthcare worker being punctured by the needle. That is, the tip of theneedle is safely protected prior to the guide needle being fully removedfrom the introducer tubing. In addition, by removing and discarding theintroducer needle 78 before the catheter 76 is introduced to thepatient, the risk of ripping the catheter is eliminated. In addition,there is no risk of the catheter snagging on the needle which couldcause a portion of the catheter to rip and remain within the patientrequiring additional surgery for removal. As a result, it is highlyadvantageous not to have any contact between the introducer needle 78and the catheter 76.

Illustrative Use of the System

Once the catheter 76 is threaded into the wound site W, the systemcomponents are connected (if not unitary) and the pump 20 is loaded andthe clamp 36 (if used) is opened so that fluid flow within the medicaltubing 70 is not occluded. The pressure imparted by the pump 20 causesthe drug to flow at a predicable rate from the pump, through the medicaltubing 70, through the catheter 76 and into the wound site W. In oneexample, the portable pain management system described above is providedin a kit which, when assembled, administers drug at a flow rate of about2 ml/hr for about 48 hours.

Although an injection syringe is preferably used to load the pump 20with the drug via the injection port 30, other suitable loading methodsmay be used. For example, a conventional gravity fed medical bag such asthose used for intravenous medical operations may be used with anelectronic or mechanical pump.

FIG. 1 shows the portable pain management system supported by a table tomore clearly show the system elements in context of use. However, theportable system is preferably placed in a location which reduces theobtrusiveness of the system. That is, tangling of the medical tubing 70or catheter 76 and accidental dislodgment of one or more elements shouldbe minimized. One such preferred location involves tucking the systeminto a sling attached to the patient's body. Another such preferredlocation involves coupling the system to a bed, bedrail or bedpost onwhich the patient lies. Yet another preferred location involvesattaching the pump to the patient's clothes through a flexible leash 122and a clip 124, housing the pump within a fanny pack, or placing thesystem within any other suitable storage device carried by the patient.

A bolus button 126 or other suitable member may be placed on the systemto allow the patient to modify the fluid flow rate. That is, the patientmay depress the button 126 to increase or decrease the fluid flow rate,or to initiate fluid flow. The button 126 may also include aconventional cut-off switch that restricts the patient's interactionwith the fluid flow rate for safety.

Alternative Catheter Insertion Assemblies

A variety of other catheter insertion assemblies may be used to achievea pierce site P spaced from the insertion site I and to advance thecatheter 76 from the pierce site P to the wound site W.

One disadvantageous assembly includes replacing the needle/tubingassembly 84 with a hollow needle (not shown). In use, the hollow needlepierces the skin and the catheter 76 is then threaded through the hollowportion of the needle to the wound site W. The hollow needle is thenwithdrawn, leaving the catheter in place at the wound site W. However,because the sharp edges of the hollow needle may rip the catheter whenwithdrawn, and because healthcare workers may stick themselves with theneedle and contract deadly diseases, use of the protective introducertubing 82, 110 is strongly preferred. Also, if this catheter insertionassembly is used with a unitary liquid dispensing system 10, a needlecannot be used because it cannot be threaded over the hub or connector72, as will be understood by those of skill in the art.

Another assembly includes replacing the introducer tubing 84 with asnug-fit catheter (not shown). At least a portion of the catheter isresilient and sized to form a snug-fit configuration around a thinneedle (not shown). The needle/catheter assembly is then pierced throughthe patient's skin and advanced to the wound site W. The needle 78 isthen withdrawn, leaving the catheter in place at the wound site W. Theneedle/catheter assembly can advance without appreciable movementrelative to each other, yet allows the needle 78 to be withdrawn fromthe catheter while keeping the catheter in place.

In another alternative embodiment, a split “T peel” needle may be usedto introduce the catheter 76 to the wound site W. In this embodiment,the T peel needle is inserted through the skin of a patient a distancefrom a wound site W and advanced to the wound site W. The catheter isthen threaded through the T peel needle into the wound site. Uponwithdrawal of the T peel needle, the needle is split and discardedleaving the catheter in place in the wound site W. In this method, theintroducer tubing 82, 110 would not be needed.

In another method, the tubing 70 extending from the pump 20 may includea Y-site connector to split the tubing into two branches. Each branchmay be placed in fluid communication with a catheter to deliver drugs toa patient. This embodiment is particularly useful when a large woundrequires two catheters to provide the drug to the entire wound.Alternatively, this method is useful when two independent wound sitesrequire administration of drugs. Each catheter then may be inserted intoa respective wound using the methods disclosed herein.

Moreover, the tubing 70 may include a Y-site connector whereby two pumpscontaining different liquids may be used to combine the two liquids foradministration of both liquids through a single catheter to a wound siteW. In this way, two liquids may be administered to a wound site using asingle catheter. Of course, by adding additional Y-sites in the tubing70, more than two catheters and/or two pumps may be used to administerfluids to a patient.

In another embodiment of the invention, the guide needle 78 may be of aprotected variety such that the tip of the guide needle is protectedupon withdrawal of the needle from the introducer tubing, thus reducingthe risk of needle sticks to healthcare workers. By reducing this risk,the risk of disease being transferred from a patient to a healthcareworker is reduced.

Through the use of an introducer tubing 110 or T peel needle, the pump20, tubing 70 and catheter 76 may be bonded together and sold as asingle unit. This unit would be advantageous for several reasons,including, but not limited to, 1) the reduced chance of leakage of thefluid, 2) the reduced risk of a patient becoming infected due to acontaminant entering the system at a connection, and 3) the pump,tubing, catheter arrangement would be easier to use as it would requireno assembly. Thus, the use of a combined pump, tubing, and catheterarrangement is within the scope of the present invention.

In the preferred embodiment, the following steps are performed toadminister an anesthetic to a wound site W. First, the pump 20 is filledwith the liquid anesthetic. To accomplish this, the clamp 36 is closedto prevent fluid flow through the tubing 70. Next, the protective cap 34is removed from the introducer port 30 of the pump 20. A syringe filledwith the liquid anesthetic is then removably secured to the introducerport 30 and the plunger of the syringe (not shown) is depressed,transferring the fluid from the syringe interior to the interior of thepump 20. This step is repeated as many times as necessary to fill thepump. Preferably, the pump contains a one-way check valve (not shown) toprevent fluid from the pump interior from exiting the pump via the port30. After the pump is filled with fluid, the cap 34 may be replaced onthe port 30. The pump may be filled using any of a variety of techniquesknown to those of skill in the art.

Optionally, a label may be secured to the pump identifying the liquidwithin the pump and specific patient information for safety reasons.

Next, the clamp 36 is opened permitting fluid to flow through the tubing70. Preferably, the tubing may have a distal end cap (not shown) whichcan be removed to permit fluid to prime the tubing 70. Once the fluidmedication has filled the entire tubing 70 and reached the lureconnector 74, the clamp 36 is closed until the pump is ready to be used.Priming the pump 20 and tubing 70 eliminates air from the system whichmay be disadvantageous if introduced to a patient. Moreover, removingair from the system is important to prevent air blocks which may inhibitcatheter performance.

Next, a syringe filled with the fluid is connected to the catheter 76via connector 72 or a catheter hub (not shown). The catheter is thenprimed until all air has been removed from the catheter.

Once the system has been primed with fluid, the guide needle 78 withintroducer tubing 82, 110 is placed within the patient. Preferably, theguide needle 78 is inserted through a pierce site in the skinapproximately 3-5 cm away from the wound site and incision site. Theintroducer needle 78 is then put through the patient's tissue to thewound site W. Next, while holding the introducer tubing 82 in place, theguide needle 78 is safely withdrawn and discarded. Importantly, theneedle is discarded prior to introduction of the catheter 76 to thesystem, thereby eliminating the risk of ripping the catheter or piercingthe skin of the healthcare worker.

Next, the catheter 76 is threaded through the introducer catheter 82,110 to the wound site. Next, the introducer catheter 82, 110 iswithdrawn from the puncture site P. As discussed previously, theintroducer catheter 110 which may be peeled from the catheter 76 isstrongly preferable to the introducer catheter 82 because it may bepeeled away from the catheter 76 and the catheter 76 may be integralwith a hub or connector 72. Using the introducer catheter 110, manysteps in the process are eliminated. For example, if the introducertubing 82 is used, the healthcare worker would need to first connect thecatheter 76 to the connector 72 in order to connect the connector 72 toa syringe to prime the catheter 76. Then, the connector 72 would need tobe removed from the catheter 76 to allow the introducer tubing 82 to beslid off of the end of the catheter 76. Thereafter, the catheter 76would need to be resecured to the connector 72 which would then beconnected to the distal end of the tubing 70 by connector 74. By using asplit introducer catheter 110, the catheter may be secured to a hub orconnector 72 prior to use which will assist healthcare workers in 1)easily priming the catheter 76, and 2) easily placing the catheter 76 influid communication with the tubing 70 and pump 20. Thus, use of thesplit introducer catheter 110 is strongly preferred over use of thecatheter introducer 82. Multiple connections and disconnections of thecatheter 76 and connector 72 increase the risk of infection to a patientand the risk of improper connections resulting in fluid leaking from thesystem prior to reaching the wound site W.

Once the catheter has been threaded into the wound site through theintroducer catheter 110 and the introducer catheter 110 has been removedand discarded, a syringe is connected to the hub or connector 72 toprime the catheter with fluid anesthetic again. Next, the catheter 76 isplaced in fluid communication with the tubing 70 and the clamp 36 isopened to commence infusion.

As will be understood by those of skill in the art, the catheter 76outside of the body of the patient should be coiled and secured to thepatient so as not to kink or pull out of the, patient. In addition, itis recommended that the flow restrictor 62 be secured to the skin of thepatient. Finally, the pump 20 may be clipped to the patient or placed ina carrying case which a patient may easily carry. Once all of the fluidhas traveled from the pump to the wound site, the infusion of anestheticis complete.

Alternative Catheter Embodiments for Uniform Delivery of Fluid

For use in many of the applications of the above methods, an improvedcatheter will now be described which provides uniform delivery of fluidmedication, and which is effective for both high flow rate and low flowrate fluid delivery.

FIGS. 10-14 illustrate an infusion catheter 320 according to oneembodiment of the present invention. Catheter 320 preferably includes aflexible support 322 (FIGS. 12-14), a non-porous membrane 324, and aporous membrane 326. The membranes 324 and 326 are wrapped around thesupport 322 to form a plurality of axial lumens between the innersurfaces of the membranes 324 and 326 and the surface of the support322, as described in greater detail below. The non-porous membrane 324defines a non-infusing section 328 of the catheter 320, and preferablycovers the support 322 from the proximal end thereof to a point 330,shown in FIG. 20. Similarly, the porous membrane 326 defines an infusionsection 332 of catheter 20, and preferably covers the support 322 fromthe point 330 to the distal end of support 322. Alternatively, thecatheter 320 may be configured without a non-porous membrane 324. Inthis configuration, the porous membrane 326 covers the entire length ofthe support 322, so that the entire length of the support 322corresponds to the infusion section of the catheter 320. The infusionsection can have any desired length. The proximal end of the catheter320 may be connected to a fluid supply 334 containing a fluid 336 suchas a liquid medication. The distal end of catheter 320 may include a cap348 (FIG. 14) defining the endpoint of the axial lumens within thecatheter 320.

In use, the catheter 320 is inserted into an anatomical system, such asa human body, to deliver fluid medication directly to a wound areawithin the anatomical system. In particular, the catheter 320 isdesigned to deliver medication throughout a generally linear segment ofthe wound area, corresponding to the infusion section 332 of thecatheter 320. Thus, the catheter is preferably inserted so that theinfusion section 332 is positioned within the wound area. By using wellknown methods, a physician or nurse may insert the catheter 320 with theaid of an axial guide wire 346 positioned within an axial guide wirelumen 344 of the catheter. Once the catheter is positioned as desired,the guide wire 346 is simply pulled back out through the proximal end ofthe catheter 320. Alternatively, th catheter 320 may be provided withouta guide wire or a guide wire lumen and inserted using the methodsdiscussed hereinabove.

FIGS. 12 and 13 illustrate a preferred configuration of the support 322.The surface of the support 322 includes interruptions such as aplurality of ribs 340 as shown in the figures. The interruptions areconfigured so that when the membranes 324 and 326 are wrapped around thesupport 322, the membranes form a portion of the walls of a plurality ofaxial lumens 338 within which the fluid 336 may flow. In a preferredconfiguration, a plurality of ribs 340 extend radially from a commonaxial center portion 342 of the support 322. The ribs 340 also extendlongitudinally along a length of the support 322, and preferably alongthe entire length thereof. In the non-infusing section 328, shown inFIG. 12, the non-porous membrane 324 is preferably tightly wrappedaround the outer edges of the ribs 340. As a result, the axial lumens338 are formed between the inner surface of the non-porous membrane 324and the outer surface of support 322. Similarly, in the infusion section332, shown in FIG. 13, the porous membrane 326 is preferably tightlywrapped around the outer edges of the ribs 340, so that the axial lumens338 are formed between the inner surface of porous membrane 326 and theouter surface of support 322.

In an alternative embodiment of the catheter 320, the porous membrane326 may be wrapped around the entire length of the support 320, thusreplacing the non-porous membrane 324. In this embodiment, the entirelength of the support 322 corresponds to the infusion section 332.According to another alternative embodiment, the support 322 may extendonly within the infusion section 332, and a tube may be providedextending from the fluid supply 334 to the proximal end of the support322. In this embodiment, the tube replaces the non-porous membrane 324and the portion of the support 322 extending within the non-infusingsection 328 of the preferred embodiment. In other words, the tubedefines the non-infusing section 328.

In the preferred configuration, the number of ribs 340 equals the numberof axial lumens 338. Although five ribs 340 and axial lumens 338 areshown in FIGS. 12 and 13, any suitable number of ribs 340 and lumens 338may be provided, giving due consideration to the goals of providing aplurality of lumens within the catheter 320, maintaining flexibility,and, if desired, maintaining the fluid independence of the lumens.Herein, the terms “fluid independence,” “fluid separation,” and thelike, when used to describe a plurality of axial lumens, simply meanthat the lumens do not fluidly communicate with each other. Themembranes 324 and 326 are preferably glued along the outer edges of theribs 340, utilizing any suitable glue, such as a medical grade glue orepoxy. This prevents the membranes 324 and 326 from slipping, whichmight occur as the catheter is inserted or removed from the anatomy.More preferably, the membranes are glued along the entire length of theouter edges of each of the ribs 340. Alternatively, the membrane may bewrapped around the support and not secured to the support by a foreignsubstance. The membrane and support may also be secured to each other byother means known to those of skill in the art. This maintains the fluidindependence of the lumens 338. If desired, an axial guide wire lumen344 may be provided within the axial central portion 342 of the support322. The guide wire lumen 344 is adapted to receive a guide wire 346which may be used to aid in the insertion of the catheter 320 into theanatomy, as described above and as will be easily understood by those ofskill in the art.

As shown in FIG. 14, the catheter 320 preferably includes an end portionor cap 348 secured to the distal end of support 322. End portion 348 maybe formed integrally with the support 322 or may be adhesively bondedthereto. Preferably, the proximal end of end portion 348 is circular andhas a diameter such that the outer surface of the proximal end of endportion 348 is aligned with the outer edges of the ribs 340 of thesupport 322, as shown. The porous membrane 326 is wrapped around theproximal end of the end portion 348. The membrane 326 is preferablyglued or secured to the end portion 348 so that fluid 336 within thelumens 338 is prevented from exiting the catheter 320 without passingthrough the walls of the membrane 326. End portion 348 blocks axialfluid flow through the distal end of catheter 320. However, end portion348 may optionally be formed from a porous material to permit some axialdispensation of fluid from the distal end of the catheter 320, ifdesired. The distal end of end portion 348 is preferably dome-shaped, asshown, to permit the catheter 320 to more easily be inserted into ananatomical region.

The support 322 can be formed from a variety of materials, giving dueconsideration to the goals of flexibility, light-weight, strength,smoothness, and non-reactivity to anatomical systems, i.e., safety.Suitable materials for the support 322 include nylon, polyamide, Teflon,and other materials known to those skilled in the art. The porousmembrane 326 is preferably a sponge-like or foam-like material or ahollow fiber. The membrane 326 may be formed from a variety of suitablematerials, giving due consideration to the goals of being flexible andnon-reactive to anatomical systems. The membrane 326 preferably has aporosity resulting in substantially uniform dispensation of fluid alongthe surface area of the infusion section 332 of the catheter 320, andhas an average pore size sufficiently small to limit the flow ofbacteria through the membrane walls. Some suitable materials for themembrane 326 are polyethylene, polysulfone, polyethersulfone,polypropylene, polyvinylidene difluoride, polycarbonate, nylon, or highdensity polyethylene. These materials are advantageously biocompatible.The porous membrane 326 may filter out unwanted bacteria from the fluidmedication as it passes through the membrane 326. It is known that thesmallest bacteria cannot pass through a pore any smaller than 0.23microns. Thus, the average pore size, or pore diameter, of the porousmembrane 326 may be less than 0.23 microns to prevent bacteria fromtraversing the membrane 326. The average pore size, or pore diameter, ofthe membrane 326 is preferably within the range of about 0.1 to 1.2microns, more preferably within the range of about 0.3 to 1 micron, andeven more preferably about 0.45 microns.

As mentioned above, the proximal end of catheter 320 may be connected toa fluid supply 334. The catheter 320 may be configured so that eachaxial lumen 338 is fluidly independent. In other words, the lumens 338would not fluidly communicate with one another. The catheter 320 may beconnected to a single fluid supply 334, so that the fluid 336 flowswithin each of the lumens 338. Alternatively, the catheter 320 may, beconnected to a plurality of separate fluid supplies so that severaldifferent fluids may separately flow within the lumens 338. According tothis configuration, each lumen 338 may be connected to a separate fluidsupply so that the total number of different fluids that may bedelivered to the anatomy is equal to the number of lumens 338.Alternatively, the fluid lumens need not be fluidly independent. Forexample, the membrane 326 may not be secured to the support 322 alongthe entire length of the support 322, thus permitting fluid 336 tomigrate between lumens 338.

In operation, the catheter 320 delivers fluid directly to the area ofthe anatomy that is adjacent to the infusion section 332. The fluid 336from the fluid source 334 is introduced into the axial lumens 338 at theproximal end of the catheter 320. The fluid 336 initially flows throughthe non-infusing section 328. When the fluid 336 first reaches theinfusion section 332, it soaks into the porous membrane 326. As morefluid 336 enters the infusion section 332, it diffuses longitudinallywithin the walls of the membrane 326 until the entire membrane 326 andinfusion section 332 are saturated with fluid. At this point the fluid336 begins to pass through the membrane 326, thereby exiting thecatheter 320 and entering the anatomy. Moreover, the fluid 336advantageously passes through the entire surface area of the porousmembrane 326 at a substantially uniform rate, due to the characteristicsof the membrane 326. Thus, the fluid is delivered at a substantiallyequal rate throughout a generally linear segment of the wound area ofthe anatomy. Furthermore, this advantage is obtained for both low andhigh pressure fluid delivery.

FIGS. 15 and 16 illustrate a catheter 350 according to an alternativeembodiment of the present invention. According to this embodiment, thecatheter 350 includes an elongated outer tube 352 and an inner elongatedtubular porous membrane 354. The tubular membrane 354 is preferablyconcentrically enclosed within the outer tube 352. More preferably, thetube 352 tightly surrounds and supports the tubular membrane 354 so thata relatively tight fit is achieved between the inner dimensions of tube352 and the outer dimensions of membrane 354. A plurality of fluid exitholes 356 are provided within the tube 352, preferably throughout theentire circumference thereof. The portion of tube 352 that includes theexit holes 356 defines the infusion section of catheter 350. The tubularmembrane 354 need only be provided along the length of the infusionsection, but could be longer. Optionally, axial exit holes may beprovided within the distal tip 358 of the tube 352. Also, a guide wireand/or guide wire lumen may be provided to aid in the insertion of thecatheter 350 into the anatomy, as will be understood by those skilled inthe art. Alternatively, any of the catheters disclosed herein may beintroduced to a wound site using the methods discussed herein (i.e., viaan introducer catheter 82, 110).

The tube 352 may be formed from any of a variety of suitable materials,such as nylon, polyamide, Teflon and other materials known to thoseskilled in the art, giving due consideration to the goals ofnon-reactivity to anatomical systems, flexibility, light-weight,strength, smoothness, and safety. In a preferred configuration, the tube352 is preferably a 20 gauge catheter tube, having inside and outsidediameters of 0.019 inches and 0.031 inches, respectively. The exit holes356 of tube 352 are preferably about 0.015 inches in diameter andprovided at equally spaced axial positions along the tube 352. The holes356 are preferably arranged so that every hole is angularly displacedabout 120° relative to the longitudinal axis of the tube 352, from theangular location of the previous hole. The axial separation betweenadjacent exit holes 356 is preferably within the range of about 0.125 to0.25 inches, and more preferably about 3/16 inch. Also, the infusionsection can have any desirable length. This configuration results in athorough, uniform delivery of fluid throughout a generally linearsegment of the wound area. Of course, the exit holes 356 may be providedin any of a variety of alternative arrangements.

The tubular porous membrane 354 is preferably a sponge-like or foam-likematerial or a hollow fiber. The tubular membrane 354 may have an averagepore size, or pore diameter, less than 0.23 microns to filter bacteria.The pore diameter is preferably within the range of about 0.1 to 1.2microns, more preferably within the range of about 0.3 to 1 micron, andeven more preferably about 0.8 microns. The tubular membrane 354 may beformed from any of a variety of suitable materials, giving dueconsideration to the goals of non-reactivity to anatomical systems,maintaining flexibility, fitting within the size constraints of the tube352, and having a porosity resulting in the substantially uniformdispensation of fluid through all of the exit holes 356 in tube 352.Some suitable materials for the membrane 354 are polyethylene,polysulfone, polyethersulfone, polypropylene, polyvinylidene difluoride,polycarbonate, nylon, or high density polyethylene. Preferable insideand outside diameters of the tubular membrane 354 are 0.010 inches and0.018 inches, respectively. In the event that a guide wire 346 isprovided, the guide wire may be a stainless steel wire about 0.005inches in diameter. The tube 352 may be secured to the membrane 354 byepoxy or other means known to those skilled in the art. Alternatively,the membrane 354 may contact the tube 352 with an interference fit andnot use other materials to secure the membrane 354 in the tube 352.

In operation, the catheter 350 delivers fluid to the region of ananatomical system adjacent to the infusion section of catheter 350. Asthe fluid flows into the infusion section, it initially soaks into thetubular porous membrane 354. As more fluid enters the infusion section,the fluid diffuses longitudinally within the walls of the tubular member354. Once the membrane 354 and the tubular space therein are saturated,the fluid passes through the membrane 354 and exits the catheter 350 byflowing through the exit holes 356 of the tube 352. Moreover, the fluidadvantageously passes through the membrane substantially uniformlythroughout the surface area of the membrane 354, resulting in asubstantially uniform flow through substantially all of the exit holes356. Thus, the fluid is delivered at a substantially equal ratethroughout the wound area of the anatomy. Furthermore, this advantage isobtained for both low and high pressure fluid delivery.

FIG. 17 illustrates a catheter 370 according to another embodiment ofthe present invention. Catheter 370 includes a tube 372 having aplurality of exit holes 376 in side walls of the tube, and a tubularporous membrane 374 concentrically enclosing the tube 372. Catheter 370operates in a similar manner to catheter 350 described above inconnection with FIGS. 15 and 16. In use, fluid medication passes throughthe exit holes 376 and then begins to soak into the porous membrane 374.The fluid diffuses longitudinally within the walls of the membrane untilthe membrane is saturated. Thereafter, the fluid leaves the membranewalls and enters the anatomy. Advantageously, the fluid is dispensed tothe anatomy at a substantially uniform rate throughout the surface areaof the membrane 374. As in the previous embodiments, this advantage isobtained for both low and high pressure fluid delivery.

FIG. 18A illustrates a catheter 360 according to another embodiment ofthe present invention. Catheter 360 is better suited for relatively highflow rate delivery of fluid to a region within an anatomical system.Catheter 360 includes a tube 362 having a plurality of exit holes 364 ofincreasing size. In particular, the more distal exit holes are larger indiameter than the more proximal exit holes. The position of the exitholes 364 on the tube 362 defines the length of the infusion section ofthe catheter 360. The infusion section can have any desired length. Theproximal end of catheter 360 is connected to a fluid supply, and a guidewire and/or guide wire lumen may also be provided for aiding in theinsertion of catheter 360 into the anatomy.

As discussed above, for high or low pressure fluid delivery, exit holesnearer to the distal end of a catheter tube generally have increasedflow resistance compared to exit holes nearer to the proximal end of thetube. Also, the fluid flowing through the more distal holes experiencesa greater pressure drop. Consequently, there is generally a greater flowrate of fluid through the more proximal holes, resulting in non-uniformfluid delivery. In contrast, catheter 360 advantageously providessubstantially uniform fluid delivery through substantially all of theexit holes 364, under relatively high flow rate conditions. This isbecause the larger size of the more distal holes compensates for theirincreased flow resistance and pressure drop. In other words, since themore distal holes are larger than the more proximal holes, there is agreater flow rate through the more distal holes than there would be ifthey were the same size as the more proximal holes. Advantageously, theholes 364 are provided in a gradually increasing size which results insubstantially uniform fluid delivery. In addition, the exit holes 364may be sized so that they combine to form a flow-restricting orifice, asdescribed below in connection with the embodiment of FIG. 22.

As compared to prior art catheters, catheter 360 is advantageouslysimple and easy to manufacture. All that is required is to drill aplurality of exit holes 364 in the tube 362. Furthermore, catheter 360can sustain greater bending than prior art catheters while maintainingoperability. In contrast to prior art catheters, such as the Wangcatheter, if the tube 362 is bent somewhat, it will still deliver fluidrelatively uniformly. This is because the tube 362 has a single lumenwith a relatively large cross-section. When the tube 362 is somewhatbent, fluid flowing within the lumen is less likely to experienceblockage and a consequent pressure change which might lead tonon-uniform fluid dispensation.

The tube 362 of catheter 360 may be formed from any of a wide variety ofmaterials, giving due consideration to the goals of non-reactivity toanatomical systems, flexibility, light-weight, strength, smoothness, andsafety. Suitable materials include nylon, polyamide, Teflon, and othermaterials known to those skilled in the art. The infusion section canhave any desired length but is preferably about 0.5 to 20 inches long,and more preferably about 10 inches long. The diameter of the exit holes64 preferably ranges from about 0.0002 inches at the proximal end of theinfusion section to about 0.01 inches at the distal end thereof. Thelargest, i.e., most distal, exit hole 364 is preferably about 0.25inches from the distal end of the tube 362. In the preferredconfiguration, the axial separation between adjacent holes 364 is withinthe range of about 0.125 to 0.25 inches, and more preferably about 3/16inch. Optionally, the holes 364 may be provided so that adjacent holesare angularly displaced by about 120° as in the embodiment of FIG. 15.Of course, if too many exit holes 364 are provided, the tube 362 may beundesirably weakened.

FIG. 18B illustrates yet another embodiment of the catheter of thepresent invention. In this embodiment, catheter 370 includes multipleexit holes 371, 372. The longitudinal distance between proximal exitholes 371 is larger than the longitudinal distance between exit holes372. By increasing the distance between holes at the proximal end of theinfusion portion of the catheter 370, and decreasing the distancebetween exit holes 372 at the distal end of the infusion section of thecatheter 370, a more even flow of fluid throughout the infusion sectionof the catheter will be achieved, especially at higher pressures as willbe understood by those of skill in the art.

Another catheter of the present invention is illustrated in FIG. 18C.This catheter 374 includes a plurality of holes 375-379 along the lengthof the catheter. The distance between the first exit hole 375 and secondexit hole 376 is larger than the distance between the second exit hole376 and the third exit hole 377. Likewise, the distance between exitholes 376 and 377 is larger than the distance between exit holes 377 and378 in the longitudinal direction along the catheter. Similarly, thedistance between exit holes 377 and 378 is larger than the distancebetween exit holes 378 and 379. Thus, by continually decreasing thedistance between exit holes while traveling distally along the length ofthe catheter, a more even flow rate of fluid through the catheter isachieved, especially at high pressures.

Of course, it is contemplated by the present inventors that one mayprovide larger or smaller exit holes or adjust the various distancesbetween various exit holes and still achieve the results of the presentinvention. Thus, any such modifications are considered within the scopeof the present invention.

FIGS. 19, 20A, and 20B illustrate a catheter 380 according to anotherembodiment of the present invention. The catheter 380 comprises a tube382, a “weeping” tubular coil spring 384, and a stop 386. The proximalend of the spring 384 is attached to the distal end of the tube 382 sothat the tube and spring each define a portion of a central lumen. Apreferably dome-shaped stop 386 is attached to and closes the distal endof the spring 384. The portion of the spring 384 that is distal to thetube 382 comprises the infusion section of the catheter 380. In anunstretched state, shown in FIG. 20A, the spring 384 has adjacent coilsin contact with one another so that fluid within the spring and below athreshold dispensation pressure is prevented from exiting the lumen byflowing radially between the coils. The spring 384 has the property ofstretching longitudinally, as shown in FIG. 20B, when the fluid pressureis greater than or equal to the threshold dispensation pressure of thespring, thereby permitting the fluid to be dispensed from the lumen by“weeping,” i.e., leaking radially outward between the coils.Alternatively, the spring may stretch radially without elongating topermit fluid to weep through the coils of the spring. Further, thespring may stretch both longitudinally and radially to permit weeping,as will be understood by those of skill in the art. Advantageously, thefluid between the coils of the spring is dispensed substantiallyuniformly throughout the length and circumference of the portion of thespring that is distal to the tube 382, i.e., the infusion section. Thecatheter 380 can be used for both high or low flow rate fluid delivery.

In use, the catheter 380 is inserted into an anatomical region so thatthe spring 384 is in a region to which fluid medication is desired to bedelivered. The spring is initially in an unstretched state, as shown inFIG. 20A. The fluid is introduced into a proximal end of the tube 382 ofthe catheter 380 and flows into and through the spring 384 until itreaches the stop 386. As fluid is continually introduced into theproximal end of the tube 382, the fluid builds inside of the spring 384.When the spring 384 is filled with fluid, the fluid pressure rises morequickly. The fluid imparts a force directed radially outward onto thespring coils. As the pressure builds, the outward force becomes larger.Once the fluid pressure rises to the threshold dispensation pressure,the outward force causes the spring coils to separate slightly so thatthe spring stretches longitudinally, as shown in FIG. 20B.Alternatively, the coils may separate radially, as discussed above. Thefluid then flows through the separated coils to be dispensed from thecatheter 380. Moreover, the dispensation is advantageously uniformthroughout the infusion section of the catheter 380. As fluid iscontinually introduced into the tube 382, the spring 384 remainsstretched to continually dispense fluid to the desired region within theanatomy. If the fluid introduction temporarily ceases, the fluidpressure within the spring 384 may fall below the threshold dispensationpressure. If so, the spring will compress so that the coils are onceagain adjacent and the fluid is no longer dispensed.

Several spring types will achieve the purposes of this invention.Suitable spring types are 316L or 402L, which can be readily purchased.In a preferred configuration, the spring 384 has about 200 coils perinch along its length. In this configuration, the spring canadvantageously sustain a high degree of bending without leaking fluidfrom within, and only a severe bend will cause adjacent coils toseparate. Thus, the spring 384 may be flexed considerably within ananatomical region without causing fluid to leak and therefore bedispensed to only one region within the anatomy. The spring 384 can haveany desired length to define the length of the infusion section of thecatheter 380. The spring may be formed from a variety of materials,giving due consideration to the goals of strength, flexibility, andsafety. A preferred material is stainless steel. In the preferredconfiguration, the inside and outside diameters of the spring are about0.02 inches and 0.03 inches, respectively, and the spring wire has adiameter of about 0.005 inches. The proximal end of the spring 384 ispreferably concentrically enclosed within the distal end of the tube382. The spring can be glued to the inside wall of the tube 382 using,for example, a U.V. adhesive, a potting material, or other bondingmaterials. Alternatively, the spring can be soldered within the tube 382or be fitted with a proximal plug and tightly plugged into the tube 382.

The tube 382 and stop 386 can be formed from any of a variety ofmaterials, giving due consideration to the goals of flexibility,light-weight, strength, smoothness, and safety. Suitable materialsinclude nylon, polyamide, Teflon, and other materials known to thoseskilled in the art.

FIG. 21 illustrates a catheter 390 according to another embodiment ofthe present invention. The catheter 390 comprises a distally closed tube392 and a “weeping” tubular coil spring 394 concentrically enclosedwithin the tube 392 so that a lumen is defined within the tube andspring. A plurality of exit holes 396 are provided along a length of thetube 392, in the side wall thereof. The length of the tube 392 includingsuch exit holes 396 defines an infusion section of the catheter 390. Theexit holes 396 are preferably provided throughout the walls of theinfusion section. The infusion section can have any desired length. Inthe preferred configuration, the axial spacing between adjacent holes396 is within the range of about 0.125 to 0.25 inches, and morepreferably about 3/16 inch. Adjacent holes 396 are preferably angularlyspaced apart by about 120°. The spring 394 is preferably enclosed withinthe infusion section of the catheter and configured similarly to thespring 384 of the embodiment of FIGS. 19, 20A and 20B. The spring 394 ispreferably longer than the infusion portion and positioned so that allof the exit holes 396 are adjacent to the spring 394. In thisconfiguration, the fluid is prevented from exiting the lumen withoutflowing between the spring coils. A stop is preferably attached to thetube to close the distal end thereof. Alternatively, the tube 392 may beformed with a closed distal end. The catheter 390 can be used for highor low flow rate fluid delivery.

In use, the catheter 390 is inserted into an anatomical region so thatthe infusion section is in a region to which fluid medication is desiredto be delivered. The fluid is introduced into a proximal end of the tube392 of the catheter 390 and flows through the spring 394 until itreaches the closed distal end of the tube 392. As fluid is continuallyintroduced into the proximal end of the tube 392, the fluid buildsinside of the spring 394. Eventually, the spring 394 becomes filled withfluid, the fluid pressure rises, and the fluid weeps through the springcoils as described above in connection with the embodiment of FIGS. 19,20A, and 20B. Moreover, the fluid flows through the spring coilssubstantially uniformly throughout the length and circumference of thespring 394. The fluid then exits the tube 392 by flowing through theexit holes 396 of the infusion section. The exit holes are preferablyequal in size so that the fluid flows at a substantially equal ratethrough the exit holes, advantageously resulting in a generally uniformdistribution of fluid throughout a desired region of the anatomy. Asfluid is continually introduced into the catheter 390, the spring 394remains stretched to continually dispense fluid from the catheter. Ifthe fluid introduction ceases temporarily, the fluid pressure within thespring 394 may fall below the threshold dispensation pressure. If so,the spring may compress so that the coils are once again adjacent andthe fluid is no longer dispensed.

In the preferred configuration, the spring 394 and tube 392 are incontact along the entire length of the spring, so that the fluid weepingthrough the spring is forced to flow through the holes 396 of theinfusion section. Preferably, one end of the spring 394 is attached tothe inside walls of the tube 392, permitting the other end of the springto be displaced as the spring stretches. The spring can be glued to thetube 392 with, for example, a U.V. adhesive, potting material, or otherbonding materials. Alternatively, an end of the spring can be solderedonto the inner walls of the tube 392. The tube 392 can be formed fromany suitable material. The inside walls of the tube 392 are preferablysmooth so that the spring can more freely stretch and compress.

FIG. 22 illustrates a catheter 400 according to another embodiment ofthe present invention. The catheter 400 comprises a distally closed tube402 having a plurality of exit holes 404 in side walls of the tube 402.The portion of the tube 402 having exit holes 404 defines an infusionsection of the catheter 400. The exit holes 404 are sized to have acombined area of opening that is smaller than the area of any otherflow-restricting cross-section or orifice of the catheter. Thus, theexit holes 404 are the flow-restrictor of the catheter 400. In use, thecatheter advantageously dispenses fluid through substantially all of theexit holes 404. A fluid introduced into a proximal end of the tube 402flows through the tube until it reaches the closed distal end thereof.At this point, the fluid builds within the infusion portion of thecatheter. The fluid is substantially prevented from flowing through theholes 404, due to their small size. Eventually, the infusion portion ofthe catheter becomes filled with fluid. As fluid is continuallyintroduced into the proximal end of the tube 402, the fluid pressurebegins to build. At some point the pressure becomes sufficiently high toforce the fluid through the exit holes 404. Moreover, the fluid flowsthrough substantially all of the exit holes 404.

In this preferred configuration, the exit holes 404 are all equal insize so that the fluid is dispensed at a substantially equal ratethrough substantially all of the holes. The holes 404 are preferablylaser drilled to achieve a very small hole diameter. A preferreddiameter of the exit holes 404 is about 0.0002 inches, or about 5microns. Numerous exit holes 404 may be provided within the tube 402.The holes are advantageously provided throughout the circumference ofthe infusion portion of the catheter 400, to more uniformly deliver thefluid throughout an anatomical region. A preferred axial spacing betweenadjacent holes 404 is within the range of about 0.125 to 0.25 inches,and more preferably about 3/16 inch. The catheter 400 can be used forhigh or low flow rate fluid delivery. The tube 402 can be formed fromany of a variety of materials known to those skilled in the art anddiscussed previously.

FIG. 23 illustrates a catheter 200 according to another embodiment ofthe present invention. Catheter 200 includes a distally closed tube 202having a plurality of exit holes 204 therein along an infusion sectionof the catheter, as in the above-described embodiments. The holes 204are desirably provided throughout the circumference of the tube 202.Enclosed within the tube 202 is an elongated member 206 formed of aporous material. Preferably, the member 206 is generally cylindrical inshape, and solid. Preferably, the member 206 is positioned within thetube 204 so that an annular space 208 is formed between the outersurface of the member 206 and the inner surface of the tube 202.Preferably, the member 206 extends from the distal end 210 of the tube202 rearwardly to a point proximal of the infusion section of thecatheter. Alternatively, the member 206 may extend along only a portionof the infusion section. The member 206 is preferably generallyconcentric with the tube 202, but non-concentric designs will achievethe advantages of the invention. Preferably, the member 206 ismanufactured of a flexible material to assist with the placement of thecatheter 200 in the body of a patient.

In operation, fluid medication flowing in the tube 202 saturates theporous member 206 and flows into the annular region 208. Once the member206 is saturated, the fluid in the member 206 flows into the region 208and out of the catheter 200 through the exit holes 204. Advantageously,since the fluid pressure is uniform throughout the annular region 208,the fluid flows substantially uniformly through all of the holes 204.There are several advantages of the annular region 208. One advantage isthat it tends to optimize the uniformity of flow through the exit holes204. Also, the member 206 may be formed from a porous material thattends to expand when saturated with liquid. If so, the member 206preferably expands into the annular region 208 without pressing againstthe tube 202. This limits the possibility of high pressure regions atthe interior surface of the tube 202, which could cause uneven exit flowof the medication within the wound site. Alternatively, the member 206may expand and come into contact with the tube 202, and still accomplishthe goals of the present invention.

The member 206 is formed of a porous material having an average poresize preferably within the range of 0.1-50 microns, and more preferablyabout 0.45 microns. The radial width W of the annular region 208 ispreferably within the range of 0 to about 0.005 microns, and morepreferably about 0.003 microns. The member 206 can be formed of any of avariety of materials, giving due consideration to the goals of porosity,flexibility, strength, and durability. A preferred material is Mentek.

The member 206 can be secured within the tube 202 by the use of anadhesive. In one embodiment, as shown in FIG. 23, the adhesive isapplied at the distal end of the member 206 to form a bond with theinterior surface of the distal end of the tube 202. Preferably, adhesiveis applied at or near the proximal end of the infusion section of thecatheter 200. Additionally, the adhesive can be applied to thecircumference of the member 206 at any longitudinal position thereof,forming a ring-shaped bond with the interior surface of the tube 202.For example, in the embodiment of FIG. 23, a ring-shaped bond 214 isprovided just proximal of the infusion section of the catheter 200.Other configurations are possible. For example, FIG. 24 shows anembodiment in which the adhesive is applied to the distal end of themember 206 to form a bond 216, and also at generally the center of theinfusion section to form a ring-shaped bond 218. FIG. 25 shows anembodiment in which the adhesive is applied only to the distal end ofthe member 206 to form a bond 220. FIG. 26 shows an embodiment in whichthe adhesive is applied only to the center of the infusion section toform a ring-shaped bond 222. Those of ordinary skill in the art willunderstand from the teachings herein that the adhesive may be applied inany of a variety of configurations. Thus, for example, adhesive at thedistal end of the catheter (i.e., 212, 216, and 220 in FIGS. 23, 24, and25, respectively) is not required.

In the current best mode of the invention, preferably two bonds areincorporated one at the most proximal hole and one at the most distalhole of the catheter. Each bond is formed with an adhesive as describedbelow.

The ring-shaped bond 214 can be formed by pouring the adhesive in liquidform through one of the exit holes 204 when the member 206 is in thetube 202. The adhesive, having a generally high viscosity, tends to flowabout the circumference of the member 206, rather than into the body ofthe member. The adhesive thus forms a ring-shaped bond with the tube202, as will be understood by those of skill in the art. Also, theadhesive plugs the exit hole 204 through which it is poured. Any of avariety of different types of adhesives will be acceptable, a preferredadhesive being Loctite.

As mentioned above, the member 206 is preferably concentric with thetube 202. FIG. 27 shows a cross-section of a catheter 200 in which themember 206 is concentrically enclosed within the tube 202.Alternatively, the member 206 may be positioned adjacent to the tube202, as shown in FIG. 28. The configuration of FIG. 28 may be easier tomanufacture than that of FIG. 27, since the member 206 does not have tobe centered within the tube 202.

Those of ordinary skill in the art will understand from the teachingsherein that the member 206 can be of any desired length and can extendalong any desired length of the infusion section of the catheter 200.For example, the member 206 does not have to extend to the distal end ofthe tube 202. Further, the proximal end of the member 206 may be eitherdistal or proximal to the proximal end of the infusion section.

When any of the catheters of the above embodiments is used, the cathetermay initially have air inside of the catheter tube. For example, thecatheter 200 shown in FIG. 23 may have air inside of the porous materialof the member 206. The introduction of liquid medication into thecatheter forces the air to flow out of the exit holes. However, this maytake several hours. If the catheter is inserted into a patient while airis inside, and liquid medication is introduced into the catheter, thepatient's wound site may receive little or no medication until air isexpelled from the catheter tube. Thus, it is preferred to run the liquidmedication through the catheter prior to inserting the catheter into apatient, to ensure that the air is expelled from the catheter prior touse. Further, with reference to FIG. 29, an air filter 224, as known inthe art, can be inserted into the catheter tubing proximal the infusionsection 226 of the catheter 200. The filter 224 prevents undesirable airfrom entering the infusion section 226 of the catheter 200.

FIGS. 30 and 31 illustrate catheter tubes having elongated exit holes orslots. These catheter tubes may be used in place of the catheter tubesshown and described above. FIG. 30 shows a tube 230 having exit holes orslots 232 that are elongated in the longitudinal direction of the tube230. The slots 232 are preferably provided throughout the circumferenceof the tube 230, along the infusion section of the catheter. Compared tosmaller exit holes, the elongated slots 232 tend to increase theflowrate of fluid exiting the catheter, by reducing the flow impedanceexperienced by the fluid. Preferably, the slots 232 may be orientedlongitudinally on the catheter body so as not to compromise thestructural integrity of the catheter 200, as will be easily understoodby those of skill in the art.

FIG. 31 shows a tube 234 having exit holes or slots 236 whose lengthsincrease along the length of the tube in the distal direction. In theillustrated embodiment, the slots nearer to the proximal end of theinfusion section of the tube 234 are shorter in length than the slotsnearer to the distal end of the infusion section. As in the embodimentof FIG. 18, the catheter tube 234 advantageously provides substantiallyuniform fluid delivery through substantially all of the exit slots 236,under relatively high flow rate conditions. This is because the largersize of the more distal slots compensates for their increased flowresistance and pressure drop. In other words, since the more distalslots are larger than the more proximal slots, there is a greater flowrate through the more distal slots than there would be if they were thesame size as the more proximal slots. Advantageously, the slots 236 areprovided in a gradually increasing length, which results insubstantially uniform fluid delivery. Further, the elongated slotsresult in generally higher exit flowrates, as in the embodiment of FIG.30.

With regard to all of the above embodiments of catheters, an independentguide wire lumen may be provided within or adjacent to the lumen(s)disclosed, as will be understood by those skilled in the art.

The catheters of the present invention can be used in various medicalapplications. With reference to FIG. 32, in one exemplary application acatheter 120 (reference numeral 120 is used to identify the catheter,but any of the above-described catheters can be used) is inserted into ablood clot 240 inside of a vein or artery 242. Preferably, the infusionsection of the catheter is within the blood clot 240. Liquid medicationis preferably introduced into the proximal end of the catheter tube.Advantageously, the medication exits the catheter 120 at a uniform ratethroughout the infusion section to dissolve the clot 240. As will beeasily understood by those of skill in the art, any of the catheterembodiments described herein may be used in a variety of applicationsincluding, but not limited to, peripheral nerve blocks, intrathecalinfusions, epidural infusions, intravascular infusions, intraarterialinfusions and intraarticular infusions, as well as in wound site painmanagement.

In addition, any of the catheters disclosed herein may be integral witha fluid line emanating from an infusion pump as opposed to being anindependent catheter designed to be connected or secured to an infusionpump.

Moreover, any of the catheters disclosed herein may be introduced to awound site through the use of an introducer catheter 82, 110 asdescribed in detail above. Thus, any of the catheters discussed hereinmay be used with the methods of providing anesthetic directly to a woundsite to provide pain management.

Although this invention has been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. Thus, it is intended that the scope of the present inventionherein disclosed should not be limited by the particular disclosedembodiments described above, but should be determined only by a fairreading of the claims that follow.

1. A system for the delivery of a fluid to a wound site of a patient,comprising: a fluid pump; a length of tubing securable to said pump; acatheter secured to said length of tubing, said catheter comprising anelongated tube having a uniform, non-expandable diameter and a closeddistal end, a distal end portion of said elongated tube defining aninfusion section, said infusion section comprising a plurality of fluidexit holes along a length of said elongated tube and a fluid permeableporous member enclosed within said elongate tube and extending alongsaid infusion section, said porous member comprising a material thatbecomes saturated with a fluid introduced into said catheter, whereinsaid porous member is secured to said tube by a ring-shaped bond thatincludes a portion extending into and closing at least one of saidplurality of exit holes, and wherein said ring-shaped adhesive bondsubstantially fills an annular space between said tube and said porousmember such that a fluid introduced into a proximal end of said tubewill flow through said member prior to being dispensed from saidcatheter by flowing through said plurality of exit holes locateddistally of said ring-shaped bond; and a peelable introducer comprisinga lumen configured to receive said catheter; wherein said pump, saidlength of tubing, said catheter and said introducer are providedtogether as a kit.
 2. The kit of claim 1, wherein said length of tubingis bonded to said fluid pump and said catheter as an integral unit. 3.The kit of claim 1, wherein said length of tubing is bonded to saidfluid pump and provided in said kit as an integral unit.
 4. The kit ofclaim 1, further comprising a filter secured to said tubing between aproximal and distal end of said length of tubing.
 5. The kit of claim 1,further comprising a flow controller secured to said tubing between aproximal and distal end of said length of tubing.
 6. The kit of claim 1,wherein said introducer comprises a guide needle and an introducertubing that defines said lumen of said introducer, said guide needleconfigured to be accommodated within said lumen.
 7. The kit of claim 1,wherein said fluid pump is an elastomeric infusion pump comprising anelastomeric bladder that at least partially defines a reservoir of saidfluid pump.